Manufacture of hydrogen chloride



May 20', 1947.

nccrbon Complex Aluminum Ohio R. F. PFENNIG ET AL 2,420,909 MANUFACTURE OF HYDROGEN CHLORIDE Filed July 2, 1943 Aluminum Containing Resldue Unsaturated all QM! INVEnITORS.

Patented May 20, 1947 2,420,909 MANUFACTURE OF HYDROGEN CHLORIDE Reuben F. Pfennig, Goose Creek, and Joseph T.

Horeczy, Cedar Bayou,

Tex., assignors to Standard Oil Development Company, a corporation of Delaware Application July 2, 1943, Serial No. 493,226

13 Claims. (Cl. 23-154) l The present invention is directed to the production of anhydrous hydrogen chloride. More particularly, it is concerned with a method for manufacturing and recovering hydrogen chloride from aqueous hydrochloric acid and aluminum chloride complexes by contacting the aqueous acid and the complexes in an organic I solvent.

The petroleum industry utilizes enormous quantities of hydrogen chloride and aluminum chloride in the various conversion processes which require these chemicals as promoter and catalyst for the reaction, respectively. For example, in the isomerization of normal parafiins to iso-parafiins, it is necessary to have present a minimum quantity of hydrogen chloride to promote the activity of the aluminum chloride catalyst. In other conversion operations in which aluminum chloride is used as a catalyst in the form of a liquid complex with hydrocarbons, hydrogen chloride is also employed to promote the reaction. This latter process employing the aluminum chloride as a liquid complex with hydrocarbons as the catalyst is especially applicable to isomerization of normal paraflinic naphthas to isoparaflinic hydrocarbons. In these operations large quantities of aluminum chloride are discarded in the spent complex employed as a catalyst. It will be obvious to the skilled worker in the art that recovery of the expensive reagents used in isomerization and conversion operations is necessary for economic reasons.

Various expedients have been suggested for handling aluminum chloride complexes and sludges discarded from the various isomerization and conversion operations. Among the numerous suggestions proposed is the treatment of aluminum chloride complexes and sludges with gaseous hydrogen chloride, chlorine and hydrogen while heating the sludges. None of the prior teachings have been entirely satisfactory in handling and utilizing the quantities of aluminum chloride complexes discarded from the aforementioned conversion operations.

In a pending application of one of us, U. S. Serial No. 489,782, filed June 5, 1943, is described a method for recovering hydrogen chloride from the spent aluminum chloride-hydrocarbon complexes by contacting the spent complex with aqueous hydrochloric acid under conditions whereby substantial amounts of the hydrogen chloride are recovered from the complex. In the 7 practice of the aforementioned pending application, the contacting was preferably carried out by the so-called powdered catalyst technique.

We have now discovered that larger quantities of hydrogen chloride may be recovered by contacting the aqueous hydrochloric acid with the spent aluminum chloride complexes dissolved in a suitable organic solvent than were obtained when proceeding in accordance with the method described in pending application U. S. Serial No. 489,782.

It is, therefore, the main object of the present invention to provide a continuous process Whereby substantially all of the chlorine available in spent'aluminum chloride complexes may be recovered by contacting the spent complexes with aqueous hydrochloric acid or other equivalent hydrolyzing -means with the complex dissolved in an organic solvent.

In general, the present invention contemplates treatment of the spent aluminum chloride-hydrocarbon complexes with a hydrolyzing agent, the spent complex being dissolved in an organic solvent which does not react with the evolved hydrogen chloride, the aqueous acid or with the aluminum chloride-hydrocarbon complex. The solvent should be ofthe type which will dissolve the complex. The aluminum chloride-hydrocarbon complexes may be obtained as a by-product from any petroleum conversion operation in Which aluminum chloride is used as a catalyst or treating agent. The present invention has particular application, however, to those liquid aluminum chloride-hydrocarbon complexes discarded from conversion operations in which pe- I troleum hydrocarbons boiling in the gasoline or lighter range are subjected to a change in molecular structure.

In its more specific aspects, our invention comprises the treatment of aluminum chloride-hydrocarbon complexes discarded from operations in which petroleum naphthas are treated with aluminum chloride-hydrocarbon complexes for improvement of octane number. In the present invention, the complex is dissolved in a solvent such as o-dichloro-benzene and the resulting solution is then contacted at a temperature of about 265 F. with vaporized aqueous hydrochloric acid or a strength between about 22 and 38%. It is understood, of course, that other temperatures may be employed depending on the boiling point of the solvent selected. In general, temperatures in the range between 212 F. and 400 F. will be found suitable. The ratio of solvent to complex should be greater than 2:1, and preferably should be in'the range of about 3:1 to 15:1. Solvent to complex ratios of about 10:1 have given excellent results.

The type of solvent employed should be one which does not react with the hydrogen chloride liberated from the hydrochloric acid and the complex charged or with the aluminum chloride-hydrocarbon complex treated. The solvent should have a relatively high boiling point, generally a boiling point above the temperature at which treatingoccurs. Furthermore, as mentioned before, the solvent should be capable of dissolving the complex. As examples of the types of 501-.

vents which are suitable in the practice of the process of the present invention may be mentioned chlorinated parafiinic and aromatic hydrocarbons, dioxane or the like. Other. types of solvents fulfilling the requirements .mentioned hereinabove may be used,

The amount of aqueous hydrochloric acidcontacted with the solvent containing the aluminum chloride-hydrocarbon complex will vary dependmg on the concentration of the aqueous hydro- Qhlhh a i e hplo ed as h rea gent. n ene t ma e ta hat. when r .0. hhh h rochlor c adher mp o ed, a arge e hi o he ac wi l, e eq ired than. when eah SQlUUQh? re. hs d- Wh n. anac d of ab 30%..hrdrqs h h q ids s use a mit 8 to 0. arts of hqheh e id bou 2 .12am of luminum chloride-hydrocarbon complex should be .1

Wh le an ty eq htact n he. em- P 9 n eat -th solut on. a uminumsh w derhrer hr a hmnl w h he'faq e us i.- rh hlh iha fli i .n eierr tq use th o nten current. pri c p of. 9w h ch he nflpwnaso v h conta in he cemplexe n ac s e sher va oriz xdmchhr id. However other mixing or contacting means may be pies} 5 al m i m l m arid? no ad Storage vessel 1 l l. is fluidly connected by means dff ihllhhd; 1mm: hr. rea in w r reh ihs. tower; ho se 'hhh n com;

prises wo o e -f T e ri hr mr hhl s.

Pa hdiy e i hhhhh m a -f he f a tihsihha l uppel P r i n! I 5 ma f balk cap plates or their equivalent. "Ihelower portion ldottreatingtower I4 is providedwith cascade plates or. similar. arrangement. of. mixing. means for. maintaining turbulence of the material fi-QWF ing downwardly fthereth'rough.

Hydrochloric acid of a strength .betweenabout 22 a11 d 38.% is introduced from tank ll by wayot lineja, pump I9 and heaterll) into the. lower pe tion of treating tower l4. Suflicient heat issupplied to the. hydrochloric acid in heate 20 so that it immediately vaporizes. on injection into treat in itower 14,. The ascendingjvaporous hydro chlo'ric acid contacts the. descending solution of. aluminum chloride-hydrocarbon complex which is madev up ina manner described below.

The, 1 aluminum chloride-hydrocarbon. complex; in storage tank ll. admixes in line (2' with ,a suite. ablel .org ani c solvent. injected thereinby way. of line,2 I. As stated 'hereinabove, aluminum. chlo-.

ride-hydrocarbon complex in solution. is intro:

duced into the top of treating'tower l4 andflows downwardly through the upper and then the lower section. While descendin through treating tower l4 substantially all of the chlorine contained in the complex dissolved in the solution reacts with the aqueous acid and gaseous hydrogen chloride is removed from tower M by way of line 22and is further-handled as will be described hereinafter.

The solvent containing the reaction product of, the aluminum chloride-hydrocarbon complex with, the hydrochloric acid leaves treating tower M by way'of line 23 and is pumped therethrough by pump 14 to settler 25 to be handled as will be described: further.

The. hydrogenv chloride leaving treating tower l4-by-way-ofline22 passes through cooler 26 in which solvent vaporized and released from treating tower I4 is condensed. The cooled product leaving cooler 26 is introduced by way of line 21 into separator 28 which is provided with line 29 r. r noyalpi. a eous h drogen. h or de and wi line a for ischare ei condens d so ent The. ccndenseds lr nt is umnedb Way 0i: rumpo ih .2-.whi h. onnc s h lin I; or moral.- ns nd. admix ure wi ha d i nal: l a i s f. hle de-hrdr arhon compl x s in:-

. deduce by w s ihe.

The solvent containing the liquid and solid, reaction products leaving treating; tower I4. is allqwed tt e under n ue ce-. 1 r iyihs s ier .Zh wh rfibith ehh et hh sm d eena um n rnre h aihihe. r sid an h at hi h. c n ai s. di so v d i yv m r l-l The umihh r ohthiniha s l d. residual a e i believed to be a compound represented try-the: rmu ah h l r A1 9 e n o ih degree f emoval. qtc-hlorihef qm e lumih mhh w 1. 3. a na wer The e t mi e.- esidualma rial 1,5-- ereesfromset e 2 by y-o r ine .3 nd. hen. may e urt e it e t d by; team ng. 0 ryn ss. for recovery or, solvent which adheres to the, solid. particlesg the dry-material may be-used as an ore for; recovery-oi I metallic aluminumpr it-may. he. ssd on roduct n: a nin m hloride r eatin he. c rged; drie rmat l a h em eratures ini re enc hlo e w e? by a uminum; hloride q h d- E9 m bnsis ati 2h$-. 1 d tate the .besbp o d e u n ne.-thesalid hterial discharge r m. se

The solvent substantially iree of. solid particles. dischargesv from settler. 25 by Wayof .line .34. and may befdivided. intoctwo. streams: one .streammay-be routed-through line. 35 by. openin valve 3,6,therein to line 21- for. recycling. andadmixture ith; l minumh orid v r carbou mplex. introduc'ed through line 7 l 2 to treating tower..l 4; the; other portion may be injected into tra -m ie ie hwe fil i he ppedwith heata nehl ahs 3B: 0 -a1 ih m tftemne a lre -an ess heh ei In fractionating tower. 31. the temperature. f the solvent is raised-so that a separation maybe made between the hydrocarbonm'aterialdissolved ingthesolvent n the solventitself. The solventb ne o -a ow oili eo n theca'se when o;d ichlorobenzen e .is employed, distills. overhead fromiractionating towers! andpasses outwardly.

through, line .3 8 is. condensed. in .-cooler. .49..

which is, connected by. way oflline Al; to .lincs 21. whereby the solvent maybe recycled ,to, the. treat ing,tower.i l.v Line .2! isproyided witnvalve. 52.. n Pump 43 Ifit. is. notfihsirfi l, to..recyc1e.the

76;;561Y8ii? distilled overhead, from frfifltionating;

p ir

tower 31, it may bedischarged fromthe system by opening valve 44 in branch line 45. In usual practice, however, the solvent will be recycled as described.

There is discharged from fractionating tower 3'! by way of line 48 an unsaturated oil which dissolves in the solvent in the reaction taking place in treating tower Hi. This unsaturated oil has a high degree of unsaturation as evidenced by a bromine number of 100 to 125. This oil polymerizes on exposure to the atmosphere with a tacky film forming thereon.

When solvent is discharged from the process through branch line 35, it will be necessary to add an equivalent amount of make-up solvent by opening valve 45 in line M which connects to the source of solvent storage not shown.

The material leaving treating tower M by way of line 23 should be kept in a high degree of turbulence to prevent settling prior to entrance to settling zone 25. If a high degree of turbulence is not maintained, line 23 and pump 24 are likely to become clogged.

While settling zone 25 usually has a suiiicient capacity so that substantially all of the solid particles drop downwardly therein and are removed from the solvent, in some instances where high charge rates are employed some of the particles may carry over with the solvent and oil leaving zone 25 by way of line 34. Therefore, it may be necessary to provide in line 34 filtering means for cleaning up the residual particles not settled out in zone 25.

The conditions of distillation in fractionating tower 31 will, of course, depend on the boiling point of the solvent used. It may be necessary in some instances to conduct the distillation under reduced pressure in fractionating tower 27 to prevent polymerization of unsaturated bodies in the solvent.

Our invention will be better understood by reference to the following runs in which a spent aluminum chloride-hydrocarbon complex resulting from the treatment of a gasoline hydrocarbon fraction with a liquid complex of aluminum chloride and hydrocarbons was treated in accordance with the present invention. In this particular run o-dichlorobenzene was employed as the solvent and hydrochloric acid of about 30% was used as the treating or hydrolyzing agent. 200 parts by weight of o-dichlorobenzene was admixed with 20 parts by weight of aluminum chloride-hydrogarbon complex. Hydrochloric acid of the strength mentioned was added to the solvent, the whole reaction body being maintained at a temperature of 265 F. Countercurrent conditions of contact were maintained until moisture began to appear in the overhead gases. The gases were cooled and measured. It was found that, of the amount of chlorine available in the aluminum chloride-hydrocarbon complex, 79% by weight had been recovered as hydrogen chloride, on the basis of 100% recovery of hydrogen chloride from the aqueous acid charged.

In another run similar to the preceding run, 200 parts of o-dichlorobenzene was employed to dissolve 20.5 parts by weight of spent aluminum chloride-hydrocarbon complex similar to that used in the preceding run. In this particular instance, steam, heated to a temperature of 265 F., was employed as the hydrolyzing agent. The reaction was conducted as described above until water appeared in the overhead gases. The overhead gases were cooled and measured and it was found 'that'81% by weight of the chlorine available in the aluminum chloride-hydrocarbon complex was recovered as hydrogen chloride.

It is obvious to the skilled worker that either aqueous hydrochloric acid or steam may be used as a hydrolyzing agent with equal success. However, it is preferred to use the aqueous hydrochloric acid as the hydrolyzing agent, since it is believed that the presence of hydrogen chloride is beneficial in that wetting of the reactants takes place more readily with hydrochloric acid than with steam. In the practice of our invention the hydrogen chloride released from the system by way of line 29 in most instances may be found to contain traces of moisture. Therefore, it will be necessary under certain conditions of operation to dry the gaseous hydrogen chloride. This may be done conveniently by passing the gaseous hydrogen chloride through a small body of sulfuric acid or equivalent drying reagent.

The nature and objects of the present invention having been fully described and illustrated, what we desire to claim as new and useful and to secure by Letters Patent is:

l. A process for the manufacture of hydrogen chloride which comprises the steps of dissolving an aluminum chloride-hydrocarbon complex in an organic solvent, the ratio of solvent to complex being at least two to one, contacting said solvent containing said dissolved complex with an aqueous hydrolyzing agent to form a reaction mixture, separating reaction products therefrom and recovering anhydrous hydrogen chloride from said reaction mixture.

2. A process in accordance with claim 1 in which said organic solvent is selected from the class of compounds capable of dissolving said aluminum chloride-hydrocarbon complex while being unreactive with the hydrolyzing agent, the aluminum chloride-hydrocarbon complex or the liberated hydrogen chloride.

3. A process in accordance with claim 1 in which the organic solvent is a chlorine-containing compound.

4. A process in accordance with claim 1 in which the hydrolyzing agent is aqueous hydrochloric acid.

5. A process for manufacturing hydrogen chloride which comprises dissolving an aluminum chloride-hydrocarbon complex in an organic solvent, the ratio of solvent to complex being in the range of 3:1 to 15:1, admixing said solvent containing dissolved aluminum chloride-hydrocarbon complex with aqueous hydrochloric acid while maintaining a temperature sufficient for reaction thereof, separating hydrogen chloride from the resulting reaction mixture, settling said solvent containing reaction bodies and recovering from said settled solvent mixture a hydrocarbon oil and solvent.

6. A process in accordance with claim 5 in which the solvent is a chlorinated compound.

'7. A process in accordance with claim 5 in which the solvent is o-dichlorobenzene.

8. In the manufacture of anhydrous hydrogen chloride, the steps of admixing an aluminum chloride-hydrocarbon complex with an organic solvent capable of dissolving said complex, contacting the resulting solution of aluminum chloride-hydrocarbon complex with aqueous hydrochloric acid under countercurrent conditions at a temperature in the range of 212 to 400 F., separately removing from said contacting stage hydrogen chloride and the solvent containing reaction products, cooling said hydrogen chloride 

